We're No Slaves to Our Senses

By Stuart Derbyshire
Spiked, August 24, 2007

Edited by Andy Ross

Making up the Mind: How the Brain Creates our Mental World
by Chris Frith
Blackwell, 2007, 232 pages

Positron emission tomography (PET) involves the injection of a radioactive isotope that rapidly decays in the bloodstream of the volunteer. As the isotope decays it emits positrons that can be detected outside the body. The brain gets its energy from the bloodstream. Areas that are more active receive more blood, so more positrons are detected from those areas. Using this technique, a picture of the brain at work can be built.

Technologies to represent brain function only provide a limited amount of detail. Imagine trying to figure out what is happening inside the Empire State Building by watching the lights go on and off. You might get some idea as to the internal function, but not much. The same problem faces those of us who hope to understand brain function.

But there is a further reason why our understanding is lagging behind expectation. The facts provided by brain imaging are the wrong sorts of facts.

Professor Chris Frith has dedicated much of his academic career to the study of schizophrenia. Frith describes schizophrenia as the consequence of damage to brain function. He argues that if we can understand how mental function comes about in people without schizophrenia, we will be better placed to understand how mental function goes wrong in people with schizophrenia.

Normal brains do all kinds of things without us being aware of it. If we were always processing sensation we would have no time for anything more interesting: "Couldn't the system be tuned so that the sensory signals always dominated our experience? Then hallucinations could not occur. In fact, this is a bad idea, for many reasons. Sensory signals are simply too unreliable. But more importantly, such domination would make us slaves to our senses."

Our minds are not drowned or dissolved by the senses. Human beings are self-located within sensory experience, but we are not sensorily immersed. Our intuition of ourselves as particular things with particular location and experience is opened up by our senses. Frith thinks our sense of the world is an illusion: "It may feel as if we have direct access, but this is an illusion created by our brain." And he is ambivalent about free will: "I am firmly convinced that I am a product of my brain ... I have a very strong experience of free will."

Frith's contentions that reality is illusory and free will is just a manufactured state of mind are both far too strong. Our limited direct access to the world is a problem because the world does not divide itself into fact-sized chunks. It is through our relationship with the world that we can come to divide it. The facts that we can lay claim to about the world are selected from an almost infinite number of potential facts, but we can have great confidence that the facts we are gathering are real.

Frith understates the role of inquiry in constructing a real representation of the world. Inquiry brings human beings into an understanding of the world that continues to more closely approximate the way the world truly is. The constraints that our brain places upon inquiry do not dictate reality but rather enable a specific viewpoint to flourish and an independent existence to announce itself.

Constraint upon our embodied action is also necessary for free will. If every action were driven by conscious agency then we would be overwhelmed by the effort of trying to control all the relevant parameters with the requisite precision just as our senses would be drowned by information if there were no filtering.

The negotiation of constraint and indeterminacy cannot be located in parts of the brain and recorded on a graph. That negotiation is an active, lived process and free will is possible because of the ability to interrogate nature. The fundamental mistake that Frith makes is to believe that agency or free will are products only of the human brain.

Magnetic Personalities

The Economist, August 30, 2007

Edited by Andy Ross

Magnetoencephalography (MEG) detects magnetic signals produced by the electrical activity of brain cells. MEG signals are in the femtotesla range, about a billionth of the strength of the Earth's magnetic field.

Apostolos Georgopoulos and his colleagues at the University of Minnesota, Minneapolis, think MEG could be adapted for medical use. In a recent paper in the Journal of Neural Engineering, they report that the general hum of brain activity might contain diagnostic information.

Dr Georgopoulos found a characteristic pattern in the magnetic fluctuations of healthy people's brains. He asked ten volunteers to stare at a point of light as they lay under his machine. Each run of the experiment used 248 sensors and every sensor took 45,000 readings over the course of a run.

He wondered whether the brains of people with neurological diseases might have different magnetic patterns. He invited patients with a clear diagnosis of one of six afflictions to lie in his machine. Then he recorded the magnetic fluctuations of their brains.

He analysed the results using discriminant function analysis. This allows complicated data to be reduced to a small number of components whose co-ordinates can be plotted on a graph. Each of the diseases produced a distinct cluster. Healthy brains produced a cluster that did not overlap with any of the diseases.